Disc players for optically reading audio or video signals from discs comprise a disc drive assembly having a turntable for rotating the disc, a clamp mechanism for holding the disc in pressing contact with the turntable, and a mechanism for transporting a signal reproduction pickup radially of the disc. To automatically set the disc in the signal reproduction position and to automatically unload the disc, the disc player further includes a disc carrying tray disposed at an opening in the front panel of the player and movable into and out of the player body, and a disc transport mechanism for reciprocatingly moving the tray between a disc unloaded position and a disc loaded position.
However, these mechanisms, when to be driven by separate motors, require several motors and drive control circuits for the respective motors. This gives rise to the problem of making the player large-sized and entailing an increased production cost.
Accordingly, Unexamined Japanese Patent Publication SHO 62-271245 discloses a disc player adapted to transport both the pickup and the disc by a single motor. With reference to FIG. 31 showing this disc player, a pickup 1 and a tray 26, each reciprocatingly movable, have attached thereto racks 94 and 95, respectively, and the rotation of the motor (not shown) is transmitted via a drive gear 90 to a drive member 91, which is formed with a gear portion 92 in mesh with the rack 94 of the pickup 1. By a change-over mechanism having a cam slit 98, pin 97, etc., the drive member 91 is coupled to a sector gear 96, which in turn is in mesh with the rack 95 on the tray 26.
During the reproduction of signals, the drive member 91 rotates counterclockwise to thereby transport the pickup 1 from the solid-line position to the brokenline position in FIG. 31. In this process, the changeover mechanism absorbs the rotation of the drive member 91, holding the sector gear 96 at rest.
When unloading the disc, the drive member 91 rotates clockwise from the solid-line position in FIG. 31, causing the change-over mechanism to rotate the sector gear 96 clockwise and thereby transporting the tray 26 to the broken-line position. In this process, the drive member 91 is held out of meshing engagement with the rack 94 on the pickup 1, with a toothless portion 93 of the drive member 91 opposed to the rack 94, so as not to transport the pickup 1.
With the disc player of FIG. 31, the pickup rack 94 is thus out of mesh with the drive member 91 during the transport of the tray 26 and is movable relative to the member 91, so that the pickup 1 is likely to move toward the outer periphery of the disc 81 away from the turntable 8, for example, when subjected to an impact from outside. If the pickup 1 is displaced during the transport of the tray 26, the rack 94 as displaced starts meshing with the drive member 91 when the pickup is to be thereafter transported. Consequently, when transported, the pickup is unable to reproduce signals normally.
On the other hand, Unexamined Japanese Utility Model Publication SHO 61-61659 discloses a disc player including a mechanism for locking the tray in the disc loaded position on completion of loading. The locking mechanism requires a lock pawl and lever means for operating the lock pawl and therefore has the problem of being complex in construction.
Unexamined Japanese Utility Model Publication SHO 59-149261 discloses a disc player adapted to reproduce signals from two types of discs which are different in diameter. The tray of the player is provided with a photosensor for discriminating one type from the other type. This disc player requires a lead wire for connecting the photosensor on the tray to a control circuit within the player body and accordingly has the drawback that the lead wire moves with the tray.
Unexamined Japanese Patent Publication SHO 60-80159 discloses a disc player having a lifter which is projected from the upper surface of the tray through a hole therein during the transport of the tray to slightly raise the disc on the tray by the force of a spring. When the disc is clamped, the lifter is lowered against the spring force for the disc to be placed on the turntable. However, when the disc is placed on the tray in the withdrawn position by being pushed down by the hand, the lifter is lowered against the spring force to position the disc at an indefinite level. This makes the user to feel uneasy.